Prof Bannister, speaking days after the discovery of C/2019 Q4 (Borisov), another similar galactic wanderer which is probably a comet, will outline her theories during her talk at this year’s New Scientist Live event at London’s ExCel on Friday. And while she stresses the asteroid is almost certainly not an alien probe, it still has numerous secrets waiting to be discovered. Prof Bannister told Express.co.uk: “All across our galaxy, planetary systems form and evolve around stars over millions, even billions of years.
“So there are many like Oumuamua, flung out by their home sun and wandering the cosmos, and when they wander past our Solar System as Oumuamua did, we can observe them and see what a comet or asteroid is like that formed at a different star: a little piece of the Galaxy that comes to us.
“We expect to discover many more interstellar worlds as new telescopes come online over the next few years.
Planetary systems each make these trillions of tiny objects, and almost all of them get flung out to wander the Galaxy – either early on in the first few million years of that system when itís buffeted around in a star cluster and while its planets are migrating, or gently slipping out and away at the end, when that star becomes a red giant and its Oort cloud of comets becomes unbound.
“We’ve been looking at how Oumuamua is cousins could become part of molecular clouds, which are the birthplaces of new stars and planetary systems.
Dr Michele Bannister’s talk will consider whether objects like Oumuamua “seeded” the galaxy
New Scientist Live is at ExCel London from October 10-13
“Having a scattering of ‘seed’ minor planets of a few kilometres in size in new-forming disks of gas and dust may make it easier to form a new round of proto-planets. It is an exciting idea and has a lot of possibilities that we’re exploring.”
When Oumuamua was spotted by astronomers last year, it made headlines all over the world, with its unusual shape prompting some to suggest it might even have been an alien probe.
Prof Bannister said: “I was really excited! As an astronomer who studies and maps out the Solar System, the possibility that we’d discover an interstellar object was always there – they’ve been predicted and discussed for decades as a natural outcome of how planetary systems form and evolve – but I never expected that I’d get to be involved in observing and studying the very first one to be found.”
Some pointed to uncanny similarities between Oumuamua and the alien spacecraft featured in Rendezvous with Rama, a novel by Sci Fi legend Arthur C Clarke.
Dr Michele Bannister will be speaking at New Scientist Live
C/2019 Q4 (Borisov) is, like Oumuamua, an intergalactic interloper
The universe is amazingly good at throwing up perfectly natural things that we just haven’t come across yet
Prof Bannister and her colleagues kept an open mind – but further analysis has indicated Oumuamua is almost certainly of natural origin.
She explained: “My job as a scientist is to look at all possibilities that explain the data I have to work with.
“But the Universe is amazingly good at throwing up perfectly natural things that we just haven’t come across yet – it is a big place, and our corner of it is small. So that is a much better place to start, and Oumuamua has a lot in common with other minor planets in our Solar System.”
“Minor planet is a general catch-all term for all small natural objects in the Solar System like asteroids and comets. I use it because Oumuamua had properties of both. Which is entirely reasonable; we know there’s a continuum of what little worlds in the Solar System are made of, between rocky bodies like asteroids, and dust-and-ice bodies like comets.
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C/2019 Q4 (Borisov) was discovered in August
After Oumuamua appeared, sci fi fans noted similarities with Rendezvous with Rama, by Arthur C Clarke
“In Oumuamua’s case I’d say from what we were able to measure in the brief time it was close enough to study, it appears to have been a more dried-out comet husk rather than something really rocky.
“Measuring the light reflected from its surface showed its surface was pretty red, which means it’s covered in the long-chain carbon molecules that we see on some asteroids and on little worlds orbiting out beyond Neptune.
“For the shape, Oumuamua was too small and distant for us to resolve it, which is when we can see a minor planet’s shape in detail. Instead we had to infer its shape from watching how Oumuamua’s brightness changed as we watched it over time, and those observations suggest Oumuamua is a bit flattened in shape – more like an overstuffed pita bread.
An asteroid factfile
“MU69, the distant and primordial little world that the New Horizons spacecraft flew by earlier this year was similarly a bit flat – it’s like two chunky pancakes nudged together. So these shapes are starting to tell us about how the smallest building blocks of planets form out of gas and dust.”
In Rendezvous With Rama, a mission is dispatched to intercept the mysterious object – and Prof Bannister said plans were already being drawn up for a mission to investigate future intergalactic mini-planets.
She said: “I think the idea of going to a new-found interstellar object is great. We have an upcoming mission with the European Space Agency, Comet Interceptor, which may be able to do exactly that!
“Comet Interceptor will launch in 2028, and will wait for a target to be found, probably by the new Large Synoptic Survey Telescope (LSST), which will look deep into the Solar System and discover comets while they are still out beyond the orbit of Saturn.
“LSST will spot on the order of one interstellar object a year. So given that LSST starts observing in 2022, we may even be able to find our mission target before we launch.
“Otherwise, we have five years from 2028 onward that the spacecraft can wait at L2, the gravitational balance point out beyond Earth, from where it can pounce, fire its thrusters to go and intercept a potential target, one that’s on a trajectory.
“We’ll get to go visit an interstellar object or a new comet from the Oort cloud up close, and see it from multiple angles with our three spacecraft.
Comet Interceptor is a mother spacecraft and two smaller daughter spacecraft, one built by JAXA, the Japanese space agency.”
Interstellar worlds: insights from Oumuamua is on the Cosmos stage on October 11 between 10.45am and 11.25am.